Suppressing Print based upon SubReport row count

rbuser

Hi there

I am using RB 17.02 build 149 with Delphi XE (that's the important
details out of the way, hopefully!)

I am designing a label, based upon a pipeline (from a Stored Procedure
which I can't change) which always contains at least 1 row.

However - only some of the rows in this pipeline may be relevant for
display on the label.

In order to constrain these relevant lines to a specific place on the
label, and to overflow onto multiple labels, I have placed the
"static"/"always printed" fields from the Pipeline into the "Main:
Header" section, and created a "SubReport1" which has a Variable within
the Detail band to show or hide the individual items for each row based
upon a number of scenarios.


When the SubReport is displaying 0 rows, I do not want the label to be
printed. The report will still need to be called, and return back to the
calling application as though the print has been successful, but it
should not print any copies to the specified printer.


Is this possible?

Thanks

Garry

nicocizik

Hi Garry,

The best option in your case would be to prevent calling Report.Print if
the certain data condition is met to skip printing that report. This
would involve analyzing the data before the label is printed to be sure
printing is necessary.

Another option would be to try to cancel the print job from within the
report if the data demands it. This method however could be tricky as
the timing of certain events can affect different aspects of generation.

I believe option 1 would be a much more robust solution that would work
for any situation.
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rbuser

Hi Nico,

Thanks as always for the prompt response.

I would like to try option 2 first (cancelling the print from within the
Report itself), as this will keep the report generation process within
the application common for all report templates we use, without putting
in specific processing paths within the application.


If you can let me know what I would need to do within the report that
*should* cancel the print, I can have an experiment with timings to make
it work - I just was unsure of whether cancelling the print from within
RB was possible.


If that's not possible, then I'll have to look at getting a specific
path put into the report generation process to skip the report printing,
but that would be my 2nd choice.


Cheers,

Garry

nicocizik

Hi Garry,

The issue with the second approach is timing. The only time (event)
that you could possibly cancel the report before the print job has
already started is the OnInitializeParameters event.

This event however fires before the report's pipeline has been opened so
you would need to manually access the pipeline and cancel the report if
the data demands it. If you are using RAP, this would need to be done
in a passthru function.

The above solution is similar to the first option I gave however it is
internal so could be used for specific templates only. Something like
the following...

var
lbPrintReport: Boolean;
begin

//ValidData() is a RAP passthru function that analyses the
Report.Datapipeline to determine if the report should be printed.

lbPrintReport := ValidData(Report);

if not(lbPrintReport) then
Report.Cancel;

end;


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rbuser

Hi Nico,

If I understood correctly, I can't do this purely from within the report
template itself, and it needs some coding to be done within the calling
application anyway?

So - that's what I've done I've just added the checks to the data
before it gets pushed to ReportBuilder - it means the data is loaded
potentially and run through twice, but at least it works.


It will mean I have to create more special cases in future, but this is
the first case in 3 years where I've needed to suppress printing...


Cheers

Garry

nicocizik

Hi Garry,


Correct.

ReportBuilder

Excellent! Pre-processing your data is the best way to go about this to
ensure your report(s) run smoothly.


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